Conventional methods of doping copper (Cu) interconnects by doping a Cu seed layer has potential limitations due to thickness requirements, doping levels, conformality, and fill performance. All of these metrics can change depending on the dopant concentration in the seed target.
Further, the thermal diffusion of alloys into trenches has typically been done at higher temperatures (e.g., above 200° C.). However, at narrow dimensions (e.g., below a 36 nanometer (nm) trench width) the via structures degrade at such higher temperatures due to stress migration—especially if no copper overburden remains.
Therefore, improved techniques for forming doped Cu interconnects are needed.